Muscle contracting apparatus



R. E. G. DEWAR MUSCLE CONTRACTING APPARATUS Oct. 22, 1940.

INVENTORY REGINALD E. a. DEWAR A TTORNEYS.

Filed Nov. 15, 1938 Patented Oct. 27 1940 UNITED STATES PATENT ol-"ricr.

nuscm conmc'rme manurus Reginald E. G: Dewar calm, assignor Oakland, toArthur Matthews, San Francisco, Application November 15, 1938, SerialNo. 240,505

Claims. (01. 128-422) mically contract and relax muscles; to provide adevice operating at relatively low potentials for creating an artificialmuscle contraction and .relaxation; and to provide a simple and e cientelectrical device for producing artificial exercise. Other objects of myinvention will be apparent or will be specifically pointed out in thedescription forming a part of this specification, but I do not ,limitmyself to the embodiment of the invention herein described, as variousforms may be adopted within the scope of the claims.

Other broad objects may be more readily understood by direct referenceto the drawin which is a schematic circuit diagram of onepreferred formof my invention.

I provide an oscillator tube I of the triode type, controlled by asingle tuned circuit 2 connected to tube l to create an oscillator ofthe "Hartley ype.

4 and grid condenser 5. Anode 6 of tube'l is provided with a positivepotential from a source, not shown, by wire I.

An intermediate tap Bfrom oscillating circuit 2 is connected to cathode9 of tube l, and the negative connection to the tube is provided, bywire l0 connected to one end of tuned circuit 2 and to the negative end.ll of the source, not

1 shown. Tuned circuit 2 is coupledto grids I! of Amplifier tubes l3preferably use accelerating grids 2|, both connected in parallel to apositive bias source indicated by terminal 22. The output of theamplifier tubes is controlled by a Kipp or relaxation oscillator 25,preferably of the gaseous diode type. One element of this tube 25 isconnected to negative source terminal ll Grid 3 is maintained at theproper bias' by a bias assembly comprising the usual resistor -of therelaxation oscillator 25.

and the other element is connected through amplifier grid condenser 28"and amplifier grid leak 21 to grids l2 of the amplifier tubes. Thefrequency of the relaxation oscillator tube 25 is controlled by a shuntcondenser 28 and fixed resistors 29, 29 in series with a variableresistor 30, all resistors being in series with a relaxation oscillatortube source, not shown, indicated by positive terminal 8|. I prefer toutilize series glow tubes across the source of power for relaxationoscillator in order to stabilize the voltage of the source, as is wellknown in the art. The output of transformer I9 is taken from secondary34 thereof through output circuit 35 which feeds a potentiometerresistor 36, the vary- 15 ing contact 81 of the potentiometer beingconnected to terminals 38 on an applicator connection board which alsocarries spaced pairs of terminals 89, each pair being connected togetherand connected to one end of potentiometer resister 36 through variableresistors 40.

Either one of terminals 38 constituting one side of output circuit 35,is utilized as a connection to a central applicator electrode ll whichis preferably applied to the spine of a patient. As

is customary with such electrodes, the metal sheet used is generallycovered with an absorbent cloth covering moistened with a bicarbonate ofsoda solution to provide goodcontact with the skin.

Terminal pairs 39" are used to supply connections to a plurality ofspaced pairs of lateral electrodes 42a, 42b and 2c, and these lateralelectrodes are preferably positioned one in each pair on each side ofthe central electrode on the patient. For example, pair 42a may bepositioned on the arms of the patient, pair 42!: may be positioned onthe hips of the patient, and pair 426 may be positioned on the legs ofthe natien Having thus described the circuit set-up, I will 'nowdescribe a preferred mode of operation.

I have found, for example, that the voltage in the output circuit 85will be sufilcient to cause muscle contraction between the limits offive and thirty volts when oscillator i is adjusted to have a frequencywithin the audible range, preferably between one and three thousandcycles per second. Under these circumstances, grids ii of the amplifiertubes would ordinarily be energized and the power fed directly into theoutput circuit to the patient continuously, if it were notffor theaction If the circuit as described is examined, it will be found thatgrids I! are isolated by condensers l4 and 26. Under these conditions,due to accretion of electrons during amplification operation,

charge of the relaxation oscillator 25 will continue cyclically at afrequency as determined by the values of resistors 29 and 30 andcapacity 28.

Accumulative blocking. is prevented by resistor- 23, although thisresistor may sometimes be dispensed with if suflicient leakage takesplace through condensers I l and 28 to prevent such a long periodblocking. However, inasmuch as grid condenser26 is connected to shuntcondenser 28 and to tube 25 on the positive side thereof, the

potential across capacity 28, as 'it rises, will overcome the cut-offbias of grids l2 and place the amplifier tubes in condition to transmitenergy therethrough from oscillator I into output circuit 35. I preferto adjust the frequency of relaxation oscillator 25 to a value of a fewcycles per minute, such as, forexample, twenty per minute, although itwill be obvious that this can be varied by varying variable resistor 30.

Thus, in output circuit 35 there will exist a rhythmical flow ofalternating current at the frequency of oscillator i, this flow varyingfrom maximum to zero at a rate of, for example, twenty cycles perminute. when all applicator electrodes are applied to a patient and bothoscillators energize, the flow of energy into the patint may beregulated by potentiometer 36 and variable resistors 40, so thatcomplete contraction of the muscles will take place during the timeenergy is present in output circuit 35, and relaxation of themuscles maytake place when amplifier tubes" are blocked.

Thus, I have provided means for rhythmically contracting and relaxingmuscles to provide artificial exercise, and at a relatively-lowpotential. I have found that at the frequencies and potentialsutilized,that the contractions produced thereby are not painful, but on thecontrary are highly effective for many purposes.

In order that the patient may be fully protected from the voltages ofthe oscillator system, I prefer to thoroughly insulate secondary 34 fromprimary I i, and have shown specifically a wide spacing thereof,indicating that purpose in the drawing I claim:

1. Muscle contracting apparatus comprising an electron dischargeoscillator tube, circuit'means connected to said oscillator tube tomaintain said tube in continuous and substantially constant oscillationat a frequency within the audible range, an electron discharge amplifiertube having control means including a grid fixedly biased to cut-ofl'current through said amplifier tube and having the control means thereofconnected to the output of said oscillator tube, a time constantoscillator'also connected to the control means of said amplifier tube,and operating at a frequency materially lower than the frequency of saidconti'nuously operating oscillator tube and with willcient power tocyclically overcome the fixed bias on the .grid of said amplifier tubeto cause said amplifier tube to pass current and to amplify the outputof said continuously operating oscillator in accordance with thewaveform of said time constant oscillator tube, and applicatorelectrodes connected tothe output of .said amplifier tube.

2. Apparatus in accordance with claim 1 wherein the continuouslyoperating oscillator is tuned to a frequency between one thousand andthree thousand cycles per second, and the time constant oscillator istuned to operate at a frequency on the order of. twenty cycles per,minute.

3. Apparatus in accordance with claim 1, wherein an isolationtransformer is positioned in the output circuit between the amplifiertube and the application means.

4. Muscle contracting apparatus comprising an electron dischargeoscillator tube, circuit means connected to said oscillator tube tomaintain said tube in continuous and substantially constant oscillationat a frequency within the audible range, an amplifier 'tube ha ng aninput including a control grid and an output, means for isolating thegrid of said amplifier tube to cause self-blocking of the output of saidamplifier tube, means for connecting the output of said continuouslyoscillating tube to the control grid of said amplifier tube, atimeconsta'nt oscillator tube,

a time constant circuit connected to said latter tube to maintain theperiod of oscillation thereof ,ata frequency on'the order oftwentywycles per wherein saidnamplifier tube control means is a singlegrid.

REGINALD E. G. DEWAR.

